Lesson Plan

Fire and Ice

A mound of melting ice cream draped with hot wax

Ice cream and hot wax represent the interactions of glaciers and lava on a model volcano.

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Grade Level:
Sixth Grade-Tenth Grade
Subject:
Climate Change, Earth Science, Environment, Geology, Glaciers, Hydrology, Landscapes, Volcanoes
Duration:
50 minutes for demonstration and discussion. For student groups, add 20-30 minutes for next day observations and discussions.
Group Size:
Up to 36
Setting:
classroom
Keywords:
erosion, glacier, ice ages, lahar, lava, lava flows, pycroclastic flow, striations, vent, volcano, volcanic eruptions, mount rainier, Mount Rainier National Park, Cascade Volcano Observatory

Overview

Students use ice cream glaciers and hot wax lava flows to simulate the interactions of glaciers and lava flows. This lesson plan is part of the "Living with a Volcano in Your Backyard" curriculum, created through a partnership between Mount Rainier National Park and the US Geological Survey Cascades Volcano Observatory.

Objective(s)

Students will:

  • Recognize that the volcano and its glaciers co-exist as a dynamic system
  • Identify the types of interactions and energy transformations that occur between glaciers and hot volcanic rocks
  • Identify some types of geologic features at Mount Rainier that area a product of glacier-volcano interactions

Background

Glaciers and Mount Rainier co-exist as a dynamic system
Mount Rainier distinguishes itself among other Cascade volcanoes because of its widespread high-altitude slopes and extensive snow and ice cover. About 88 square kilometers (34 square miles) of snow and ice cover the mountain at summer’s end. Glaciers have covered Mount Rainier over much of the volcano’s 500,000-year lifespan, creating a dynamic system. The volcano provides high-elevation slopes that are conducive to glacier formation and glacial erosion. Volcanic eruptions can melt snow and ice, even while glaciers influence the movement of lava flows. A general list of mechanisms of influence between glaciers and volcanoes is shown in the sidebar. This information is depicted in graphics “Glaciers on Mount Rainier,” “Columbia Crest Summit,” and “Glacier-Volcano Interactions.”

Ice-age glaciers envelop Mount Rainier
To understand the extent to which hot volcanic rocks have interacted with surrounding glaciers, we need to put on our "glacier glasses" and envision landscapes largely buried by ice. During ice ages that occurred repeatedly between approximately 1.8 million and 11,000 years ago, large ice sheets covered northern Europe and much of Canada and the northern United States, including the Puget Sound area. Mountain ranges in the western United States, including the Cascades were mantled by extensive glaciers. Some of the glaciers on Mount Rainier were hundreds of meters (1,000 feet or more) thick on the flanks of the volcano and almost 1,000 meters (3,000 feet) thick in valleys at the base of the cone. Mountain glaciers coalesced and flowed for one hundred kilometers (sixty miles). Glacier ice covered the locations of the present day communities of Ashford, Alder, Green water, and Carbonado. Around 15,000 years ago, these enormous glaciers began to thin and recede into existing valleys. Their descendants cover much of Mount Rainier today. View the extents of glaciers then and now in the graphic "Maximum Extent of Glaciers on Mount Rainier During the Ice Ages."

 

Mount Rainier erupted repeatedly while buried by ice-age glaciers
Mount Rainier erupted repeatedly during past ice ages. The co-existence of volcanic and glacial processes led to a variety of interactions that shaped the mountain in a unique way. The origins of these features can be understood only when the interactions of the glaciers and volcanic forces are recognized.

 

When lava meets ice
During times of extensive glaciation, lava poured repeatedly from the summit vent of Mount Rainier and encountered glaciers. In the contest between lava flows, rock, and ice, glaciers at first appear to be less durable. In theory, a lava flow can melt about ten times its volume of ice, though it rarely does so. We commonly think of lava flows as bullish, relentless, and unstoppable. However, observations at ice-clad volcanoes around the world prove that glaciers can survive the onslaught of heat from lava flows. In some situations, glaciers can exert some control over the movement of lava flows, and as such are the architects of Mount Rainier. Consider these mechanisms.

 

  • Lava flows tumble and disintegrate on steep slopes Lava that flows over steep slopes often breaks apart and plunges onto the glacier, where it cools as rock debris. Sometimes the fragmenting lava flow forms a turbulent avalanche of scorching hot rock and gas called a pyroclastic flow, which can sweep across the snow and ice. Incorporation of snow and ice into the pyroclastic flow can cause the flow to transform into a volcanic mudflow (lahar). Lahar layers are found in river valleys that extend from Mount Rainier.
  • Ice-age glaciers act as physical and thermal barriers to lava flows An advancing lava flow melts downward through thick ice until it contacts bedrock, where it chills and hardens, confined within the glacier. After the eruption, glacier ice often flows across the hardened lava flow. By this mechanism, Mount Rainier gains volume, and retains its glacier cover. Some of these lava flows, now partially eroded, are visible as ledges on the flanks of Mount Rainier.
  • Thin ice and ice-free regions allow lava flows to travel far Lava encounters less resistance in the thin ice and ice-free ridges between thick valley glaciers. The lava flow's outer skin cools and hardens, while the interior of the flow remains fluid and travels many kilometers (miles) from the base of the volcano. Over time, successive stacks of elongated lava flows have built ridges—from the bottom up—in a pattern that radiates from the cone of Mount Rainier. Paradise Ridge, Mazama Ridge, Rampart Ridge, and Emerald Ridge are some examples of this phenomenon. This interaction is depicted in the graphic "How Lava Ridges are Made." The phenomenon can happen only when glaciers envelop Mount Rainier, such as during an ice age.
More about glaciers
A glacier is a large mass of flowing ice formed by the compaction and recrystallization of snow that has accumulated over a period of years. When snow crystals land atop one another their fragile edges snap and break. Pressure from overlying snowpack settles the crystals, squeezes out adjacent air pockets, forces them to liquefy and then recrystallize as ice. By these processes, delicate snow crystals transform into a strong lattice of ice crystals that has sufficient strength to transform the landscape.

 

Glaciers as sculptors
Glaciers are well known as sculptors of the landscape, but the true artist is rock debris encased within the ice. Landslides and rock fall produce rock debris that drops onto the glacier surface. Winter snow falls bury the rock debris. Snow surrounding this rock debris transforms to ice. Eventually some of the entrapped rocks touch the valley floor and walls where they scrape and polish, as with grit in a gem polishing machine. Millennia of erosion by glaciers are responsible in part for the characteristic U-shaped valleys. See glacial scratches (striations) depicted in the graphic "Glacial Scratches (Striations) on Lava Rock at Mount Rainier."

 

Present-day glaciers at Mount Rainier
While Ice-Age glaciers have thinned and receded dramatically over the last 15, 000 years, Mount Rainier still hosts one of North America's largest single peak glacier systems. The present glaciers consist of approximately 4.4 cubic kilometers (one cubic mile). For scale, imagine an ice cream scoop the size of Seattle's Safeco Field sports stadium. Removing all the perennial (long-lasting) snow and glacier ice from Mount Rainier would require 2,600 stadium-sized scoops! Envision this also as an ice cube one mile on a side. The volume of perennial snow and glacier ice on Mount Rainier is equivalent to the amount of ice on all the other Cascade volcanoes combined.

Materials

Graphics to illustrate the ideas discussed in the lesson plan.

Procedure

Assessment

Use the questions in the "Fire and Ice Simulation" to assess students' thinking as it progresses through recognition that glaciers influence the landscape on a volcano. Note how students' understanding develops from general observations of the volcano model to recognition of the processes that shape an actual ice-covered volcano. As the activity progresses, students should recognize that the volcano and glaciers co-exist as a dynamic system and that many geologic and hydrologic features on the volcano are the results of glacier-volcano interactions. Students should begin to think more globally, and recognize that glaciers can influence the shape of glacier-clad volcanoes worldwide. To further assess their understanding, instruct students to write a summary paragraph about glacier-volcano interactions.

 

Park Connections

Glaciers have covered Mount Rainier over much of the volcanoes 500,000 year lifespan, creating a dynamic system between the active volcano and the glaciers.

 

Extensions

  • Instruct students to conduct research projects about glacier-volcano interactions. Students can visit websites listed on the Internet Resources List to identify landscape features that are products of glacier-volcano interactions at Cascade volcanoes, Iceland and elsewhere.
  • Engage the class in a discussion of energy transformations using these concepts: As the blocks of lava begin to avalanche down the mountainside, the lava begins to accelerate. If you've ever tried to carry a large block up a mountain, you know that it takes a lot of energy! Once you drop that block down the mountain side and it begins to roll, the energy that it took to lift it up the mountain is converted into kinetic energy—the energy of motion.
  • Engage the class in a discussion of heat transfer between lava and glacier ice along the following concepts: Many lava flows that issue from steep-sided volcanoes break up into blocks and rubble that avalanche down the slope and mix with snow and ice. The melting of snow and ice by this process has the potential to create lahars that travel great distances beyond the slope of the mountain and threaten nearby communities.

Additional Resources

Crandell, D.R., and Miller, R. D., 1974, Quaternary stratigraphy and extent of glaciation in the Mount Rainier region, Washington: U.S. Geological Survey Professional Paper 847, 59 p.

 

Driedger, C.L., 1986, A visitor's guide to Mount Rainier glaciers: Pacific Northwest National Parks and Forests Association, 80 p.

 

Driedger, C.L., and Kennard, P.M., 1986, Ice volumes on the Cascade volcanoes: Mount Rainier, Mount Hood, Three Sisters, and Mount Shasta: U.S. Geological Survey Professional Paper 1365, 28 p.

 

Driedger, C.L., 1993, Glaciers on Mount Rainier, U.S. Geological Survey Fact Sheet, Open-File Report 92-474, 2 p.

 

Lescinsky, D.T., and Sisson, T.W., 1998, Ridge-forming, ice-bounded lava flows at Mount Rainier, Washington: Geology, 26, pp. 351-354.

 

Lescinsky, D.T., and Fink, J.H., 2000, Lava and ice interaction at strato volcanoes: use of characteristic features to determine past glacial extents and future volcanic hazards: Journal of Geophysical Research, v.105, 23, pp. 711-23,726.